Centrifugal treatment of liquids



Feb. 14, 1928.

K J SVENSSON ET AL GENTRIFUGALTREATMENT 0F LIQUIDS Filed Deo. 14. 1925Pet.. i4, 192e.

` ITED STATES atente LP A T Li L,

u i" i n narnia nein swnnnn.

` CENTRIFUGAL TREATMENT 01E' LIEGIUIIIDS.

Application led December i4, 1926, Serial No. 154,680, and in dweilenJanuary 1l, 19Std,

`When purifying or separating liquids by centrifugal treatment it isoften necessary, in order to obtain a high separating ellieiency of thecentrifugal drum, to heat said liquids to a predetermined temperaturebefore they are introduced into the centrifugal drum, and this isespecially the case with thick oils as the temperature has a greateffect on their viscosity. A very common method to employ whenseparating such liquids is to pass them through an electric heater'before feeding them into the drum. For oils containing solid impurities,such as slime, sludge and the like, it is also advantageous to mix themwith a greater or smaller quantity of water or of some other suitableliquid which is heavier than the oil and which, during its separation inthe drum, extracts the solid impurities suspended in the oil', thus-facilitating separation. Usually this additional liquid or so-calledwash is mixed .with the oil in a tank, from which the mixture is pumpedor conducted in some other way into the centrifugal drum where the washis separated together with other fluid or solid heavy impurities.

One disadvantage of using electric heaters, however, is that if thesupply of liquid should stop, for instance when the feed tank isemptied, and the electric current be not switched od immediately thequick temperature rise causes the heater elements to burn out. lnorderyto prevent this, automatic thermo-switches are sometimes used but,as a rule, these are very expensive.

rllhe present invention has for its object a simple and cheaparrangement by which the risk of burning out electric heaters iscompletely eliminated, a homogeneous mixture of the liquids to beseparated and wash is obtained always, together with a thorough washingof them, and only a relatively sinall amount of washing liquid is used,thus saving wash and at the same time reducing the electric powerconsumption in the heater.

According to the present invention the improved arrangement comprises acentrifugal separator, a feed pump therefor, one -or more electricheaters situated in the feed pipe line of the separator, either or allof them on the suction side, or all on the discharge side, of the pump,or one -or more on both sides of the pump, one or more receptacles foradditional liquid or wash and the necessary feed piping with valves orcocks, wherein the suction pipe line from the wash receptacle orreceptacles tothe feed pump is connected with the suction pipe line forthe liquid to be purified or separated in such a way that the feed pumpcan suck suitable proportions from the two pipe lines simultaneously, orwash only, if the supply from the other pipe line should stop, andwherein the two liquids or liquid mixtures pass through the heater orheaters in a mixed state or are introduced separately into the heater orheaters and mixed before they are led into the centrifugal apparatus inorder to be separated or purified. i

Figures l and 2 of the accompan ing drawings show in diagrammatic sideallevation two diderent arrangements according to the present invention.

ln both fi ures: a is a tank or container for the liquid to be puried, ba smaller container for washing liquid, c a centrifugal separator ofknown type having a feed vessel al, a discharge pipe c for the puriedliquid and a discharge pipe for separated impurities and wash whilst gis an electric heater having a feed pipe It leading to the feed vessel dof the separator c. 'l`he tank b is arranged as a settling tank and hasa vertical bae j extending almost to its bottom, an outlet situated somedistance above 'said bottom, and an inlet m at its top into which theliquid discharged from the pipe f is introduced. ln this tank b most ofthe separated impurities discharged with the wash will settle down andonly the purest part of the liquid therein will be discharged throughthe outlet k. n is a drain cock in the bottom of the tank for removal ofthe settled impurities.

In the arrangement shown in Figure 1 a feed pump o has a discharge pipep leading to the heater g, whilst a pipe Q leads from the tank a to thepump o .and is provided with a control valve or cock 'l' said pipe gbeing arranged so that a part thereof is on a higher level than theinlet of the pump o. The outlet k of the tank b is connected with thepump o by a pipe a furnished with a valve or cock t, the tank b being soarranged that the normal level, u of the liquid therein is higher thanthe inlet to the pump o.

The working of the plant when purifying @lid oil, for instance, withwater as the washing li uid isI as follows e centrifugal separator c andthe pump o having been started, the cock t is opened and the electriccurrent for switched on; .water is thus pumped through the heater `g,heated, and delivered through the pipe z, to the feed vessel` 4 andthence to the drum of the separator c, heats its parts and forms thenecessary water seal in the drum before the oil can be fed in. The valver for the oil is then opened and the two valves r and t are adjustedsothat suitable proportions of the two liquids are drawn in and pumpedup through the heater g into said drum, wherein the water andother'iinpurities are separated from the oil and discharged through thepipe f to the tank b in order to be cleaned to a certain extent, andthen returned b the pi e s to the pump o. The purified oil is disc argedthrough the ipe e and collectedin a suitable receptac e, only the inlet'v of which is shown, or if it is necessary to purify the oil more thanonce it is discharged into the tank a.

If, for any reason the oil feed through the pipe g should cease, thepump o would continue topump washing water through, the heater g as thepipe g and liquid level u in the4 `tank b are arranged relatively to thepump o as described above,.thus there is no risk of burning out theheater g.

In the arrangement shown in Figure 2, w is a p ump for the liquid to'beseparated, a suction pipe leading from the tank a to the pump tw andprovided with a control valve or cock y, a a pump for washing liquidonly, and connected with the tank b by a suction pipe se', provided witha valve t.

The discharge outlets of the pum s fw and a are connected with .a commondischarge pipe p leading tothe heaterg.

The action of .the arrangement shown in Figures 1 and 2 is much thesaine althou h the position of the pump fw relatively to t e ipe ai andto the level u of the li uid in tank is of no importance as the suctionsides of the two pumps are quite independent of one another. Y

Although the arrangement shown in Figure 2 ,is a little more expensivethan that shown in Figure 1, it presents advantages when treatingliquids which emulsify easily by the violent the heater g is Y agitationwhich takes place inside a pump. ,This risk is obviated entirely in thearrangement shown in Figure 2 as the liquids are not mixed until theyhave passed through the pumps fw and a.

Both arrangements can be used also in cases where a washing is notdesired or necessary, by leaving the valves t and shut, though there isthen' a risk of burning the heater g.

Although only two arrangements of the present invention are shown,considerable variations can be made within the scope of the invention.For instance, the heater g can be situated on the suction side insteadof no the discharge side ofthe pump or pumps, the different liquids canbe introuced separately into the heater and mixed there and so on.

1. An arrangement for the centrifugal separation of liquids containingsolid particles in suspension, comprising centrifugal separatingapparatus, pumping means for supplying thereto said liquids to beseparated, and electric heating apparatus for heating said liquidsbefore delivery to the separator, said pumping means being provided withtwo lines of suction piping for the simultaneous supply to the electricheating apparatus of the liquidto be separated and a wash liquid, thearrangement being such that should the supply of liquid to be separatedbe interrupted, the wash liquid will continue to be supplied, to protectsaid heating apparatus.

2. An arrangement for the centrifugal separation of liquids containingsolid particles in suspension, comprising centrifugal separatingapparatus, pumping means or supplying thereto said liquids to beseparated, electric heating apparatus for heating said liquids beforedelivery to the separator, delivery pipingv from the pumping means tosaid heating a paratus, said pumping means being provi ed with two linesof suction iping for the simultaneous delivery to the e ectric heatingapparatus of the liquid to be separated and a wash liquid, thearrangement being such that should the supply of liquid to be separatedbe interrupted, the wash liquid will continue to be supplied, to protectsaid heating apparatus.

KARL JOHAN SVENSSON. KARL AXEL PATRIK NORLINQ

